Anisotropic electrically conductive film

ABSTRACT

An anisotropic electrically conductive film has a structure wherein the electrically conductive particles are disposed on or near the surface of an electrically insulating adhesive base layer, or a structure wherein an electrically insulating adhesive base layer and an electrically insulating adhesive cover layer are laminated together and the electrically conductive particles are disposed near the interface therebetween. Electrically conductive particle groups configured from two or more electrically conductive particles are disposed in a lattice point region of a planar lattice pattern. A preferred lattice point region is a circle centered on a lattice point. A radius of the circle is not less than two times and not more than seven times the average particle diameter of the electrically conductive particles.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/383,234 filed Apr. 12, 2019, which is a continuation of U.S. patentapplication Ser. No. 15/988,065 filed May 24, 2018, which is acontinuation of U.S. patent application Ser. No. 15/523,438 filed May 1,2017, now U.S. Pat. No. 10,026,709 issued on Jul. 17, 2018, which is aNational Stage Application of PCT Application No. PCT/JP2015/082221filed Nov. 17, 2015, which claims priority to Japanese PatentApplication No. JP2014-232934 filed Nov. 17, 2014, the entiredisclosures of which arc hereby incorporated by reference in theirentireties.

TECHNICAL FIELD

The present invention relates to an anisotropic electrically conductivefilm.

BACKGROUND ART

An anisotropic electrically conductive film having electricallyconductive particles dispersed in an electrically insulating resinbinder is widely used for mounting electronic components such as ICchips on a wiring board and the like. However, in such an anisotropicelectrically conductive film, it is known that the electricallyconductive particles are present in a state of being connected oraggregated with each other. Therefore, in the ease where the anisotropicelectrically conductive film is applied to the connection between theterminals of the wiring board and the terminals of the IC chip havingnarrowed pitches upon miniaturizing and reducing the weight ofelectronic devices, a short circuit may occur between the adjacentterminals due to the electrically conductive particles present in astate of being connected or aggregated in the anisotropic electricallyconductive film.

Conventionally, a film, in which electrically conductive particles areregularly arranged, is proposed as an anisotropic electricallyconductive film adapted to such a narrow pitch. For example, ananisotropic electrically conductive film obtained as follows has beenproposed: An adhesive layer is formed on a stretchable film and theelectrically conductive particles are densely filled in a single layeron the surface of the adhesive layer. The film is then biaxiallystretched until the distance between the electrically conductiveparticles becomes a predetermined distance to arrange the electricallyconductive particles regularly. Then, an electrically insulatingadhesive base layer, which is a constituent element of the anisotropicelectrically conductive film, is pressed against the electricallyconductive particles, and the electrically conductive particles aretransferred to the electrically insulating adhesive base layer (PatentLiterature 1). Alternatively, the anisotropic electrically conductivefilm obtained as follows has also been proposed: Electrically conductiveparticles are dispersed on a concave portion forming surface of thetransfer mold having a concave portion on its surface. The concaveportion forming surface is then squeezed to hold the electricallyconductive particles in the concave portion, and the adhesive filmformed with the adhesive layer for transferring is pressed thereon fromabove to primarily transfer electrically conductive particles to theadhesive layer. Next, an electrically insulating adhesive base layer,which is a constituent element of the anisotropic electricallyconductive film, is pressed against the electrically conductiveparticles deposited on the adhesive layer, and the electricallyconductive particles are transferred to the electrically insulatingadhesive base layer (Patent Literature 2). In these anisotropicelectrically conductive films, generally, an electrically insulatingadhesive cover layer is laminated on the surface of the electricallyconductive particle side to cover the electrically conductive particles.

CITATION LIST Patent Literature

Patent Literature 1: WO 2005/054388

Patent Literature 2: Japanese Unexamined Patent Application PublicationNo. 2010-033793A

SUMMARY OF INVENTION Technical Problem

However, the electrically conductive particles tend to aggregate due tostatic electricity or the like to form secondary particles; thus, it isdifficult for the electrically conductive particles to be presentisolated all the time as primary particles. Therefore, the followingproblems arise in the techniques of Patent Literatures 1 and 2. That is,in the case of Patent Literature 1, there was a problem that it isdifficult to densely pack electrically conductive particles on theentire surface of the stretchable film in a single layer with nodefects; thus, the electrically conductive particles may he packed inthe stretchable film in an aggregated state, thereby causing a shortcircuit; or a region, in which no electrically conductive particles arepacked (so-called “loss”) may be created, thereby causing a poorconduction. In the ease of Patent Literature 2, there was a problem thatif the concave portion of the transfer mold is covered with electricallyconductive particles having a large particle diameter, the electricallyconductive particles are removed by a subsequent squeegee, a concaveportion that does not bold the electrically conductive particles may becreated, and “loss” of electrically conductive particles” may occur inthe anisotropic electrically conductive film causing a Poor conduction;Or, conversely, if a large number of small electrically conductiveparticles are pressed in the concave portion and transferred to theelectrically insulating adhesive base layer, an aggregation of theelectrically conductive particles may occur, and further, theelectrically conductive particles located on the bottom side of theconcave portion may not be in contact with the electrically insulatingadhesive base layer; and thus, the electrically conductive particles maybe dispersed on the surface of the electrically insulating adhesive baselayer, resulting in a loss of a regular arrangement, causing a shortcircuit and a poor conduction.

An object of the present invention is to overcome the above-mentionedproblems in the prior art, and to provide an anisotropic electricallyconductive film which is free of problems such as “loss” or“aggregation” of electrically conductive particles that should bearranged in a regular pattern and in which occurrences of a shortcircuit or a poor conduction are significantly suppressed.

Solution to Problem

The present inventors have found that the object described above can beachieved by disposing the electrically conductive particle groupscomposed or a plurality of electrically conductive particles in alattice point region of a planar lattice pattern when disposingelectrically conductive particles in a lattice point of a planarlattice. Thus, the present invention was accomplished based on thesefindings. Furthermore, the present inventors also found that such ananisotropic electrically conductive film can he produced by transferringand depositing a plurality of electrically conductive particles on a tipof the concave portion of the transfer body, which has a concave portionformed on its surface, instead of disposing the electrically conductiveparticles in the concave portion of the transfer body. Thus, aproduction method of the present invention was accomplished based onthese findings.

That is, the present invention provides an anisotropic electricallyconductive film having a structure, in which electrically conductiveparticles are disposed on or near the surface of an electricallyinsulating adhesive base layer, wherein

-   -   an electrically conductive particle group is configured front        two or more electrically conductive particles, and    -   the electrically conductive particle group is disposed in a        lattice point region of a planar lattice pattern.

In addition, the present invention provides an anisotropic electricallyconductive film having a structure, in which an electrically insulatingadhesive base layer and an electrically insulating adhesive cover layerare laminated together and electrically conductive particles aredisposed near the interface therebetween, wherein

-   -   an electrically conduct e particle group is configured from two        or more electrically conductive particles, and    -   the electrically conductive particle group is disposed in as        lattice point region of at planar lattice pattern.

The present invention also provides a method of producing an anisotropicelectrically conductive film having a structure, in which electricallyconductive particles are disposed on or near the surface of theelectrically insulating adhesive base layer, comprising the followingsteps (i) to (iv):

step (i)

-   -   preparing a transfer body having a convex portion corresponding        to a lattice point region of a planar lattice pattern, foraged        on the surface thereof;        step (ii)    -   forming two or more slightly adhesive portions on the top        surface of the portion of the transfer body;        step (iii)    -   depositing electrically conductive particles on the slightly        adhesive portion of the convex portion of the transfer body; and        step (iv)    -   transferring the electrically conductive particle to the        electrically insulating adhesive base layer by overlapping and        pressing the electrically insulating adhesive base layer on the        surface of the transfer body on the side on which the        electrically conductive particles are deposited. Note that, in        step (iv), the transferred electrically conductive particles may        be further pushed into the electrically insulating adhesive base        layer 11.

The present invention also provides a method of producing an anisotropicelectrically conductive film having a structure, in which theelectrically insulating adhesive base layer and the electricallyinsulating adhesive cover layer are laminated together and theelectrically conductive particles are disposed near the interfacetherebetween, comprising the following steps (i) to (v):

step (i)

-   -   preparing a transfer body having a convex portion corresponding        to a lattice point region of a planar lattice pattern, formed on        the surface thereof;        step (ii)    -   forming two or more slightly adhesive portions on the top        surface of the convex portion of the transfer body;        step (iii)    -   depositing electrically conductive particle on the slightly        adhesive portions of the convex portion of the transfer body;        step (iv)    -   transferring the electrically conductive particle to the        electrically insulating adhesive base layer by overlapping and        pressing the electrically insulating adhesive base layer on the        surface at a side of the transfer body on which the electrically        conductive particles are deposited; and        step (v)    -   laminating an electrically insulating adhesive cover layer to        the electrically insulating adhesive base layer, on which the        electrically conductive particles are transferred, from the        side, on which the electrically conductive particles are        transferred.

Furthermore, the present invention provides a connecting structure body,in which a terminal of a first electronic component and a terminal of asecond electronic component are anisotropically electricallyconductively connected by the anisotropic electrically conductive filmof the present invention.

Advantageous Effects of Invention

In the anisotropic electrically conductive film of the presentinvention, two or more electrically conductive particles are groupedtogether to configure electrically conductive particle groups, and alarge number of electrically conductive particle groups are disposed ina lattice point region of a planar lattice pattern. Therefore,application of anisotropic electrically conductive film of the presentinvention to the anisotropic electrically conductive connection canachieve satisfactory initial conductivity and conduction reliabilityafter aging, and can suppress the occurrences of short circuit.

Further, in a method of producing an anisotropic electrically conductivefilm of the present invention, a transfer body is used that has a convexportion corresponding to a lattice point region of a planar latticepattern, formed on the surface thereof, and at least two slightlyadhesive portions are formed on the top surface of the convex portion ofthe transfer body. The electrically conductive particles are thendeposited on the slightly adhesive portions, and then the electricallyconductive particles are transferred to the electrically insulatingadhesive base layer. Thus, the electrically conductive particle groupsconfigured from two or more electrically conductive particles aredisposed in a lattice point region of a planar lattice pattern.Therefore, use of anisotropic electrically conductive film obtained bythe production method of the present invention can achieve anisotropicelectrically conductive connection while significantly suppressingoccurrences of short circuit and poor conduction between the IC chip andthe wiring board having narrow pitches.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a cross-sectional view of an anisotropic electricallyconductive film according to an embodiment of the present invention.

FIG. 1B is a cross-sectional view of the anisotropic electricallyconductive film according to an embodiment of the present invention.

FIG. 2A is a perspective plan view of the anisotropic electricallyconductive film according to an embodiment of the present invention.

FIG. 2B is a perspective plan view of the anisotropic electricallyconductive film according to an embodiment of the present invention.

FIG. 2C is a perspective plan view of the anisotropic electricallyconductive film according to an embodiment of the present invention.

FIG. 2D is a perspective plan view of the anisotropic electricallyconductive film according to an embodiment of the present invention.

FIG. 2E is a perspective plan view of the anisotropic electricallyconductive film according to an embodiment of the present invention.

FIG. 3A is a diagram illustrating steps of a production method accordingto an embodiment of the present invention.

FIG. 3B is a diagram illustrating steps of a production method accordingto an embodiment of the present invention.

FIG. 3C is a diagram illustrating steps of a production method accordingto an embodiment of the present invention.

FIG. 3D is a diagram illustrating steps of a production method accordingto an embodiment of the present invention.

FIG. 3E is a diagram illustrating steps of a production method accordingto an embodiment of the present invention.

FIG. 3F is a diagram illustrating steps of a production method accordingto an embodiment of the present invention and a schematic sectional viewof the anisotropic electrically conductive film according to anembodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, the anisotropic electrically conductive film of the presentinvention will be described in detail with reference to the drawings.

<Anisotropic Electrically Conductive Film>

The anisotropic electrically conductive film according to an embodimentof the present invention is illustrated in FIG. 1A (cross-sectionalview) or FIG. 1B (cross-sectional view) and FIG. 2A (perspective planview). In the case of FIG. 1A, the anisotropic electrically conductivefilm 10 according to an embodiment of the present invention has a singlelayer structure, in which electrically conductive particles 13 aredisposed on or near the surface of an electrically insulating adhesivebase layer 11. Here, “the electrically conductive particles 13 aredisposed on the surface of the electrically insulating adhesive baselayer 11” means that a part of the electrically conductive particles 13is pressed and disposed into the electrically insulating adhesive baselayer 11, and “the electrically conductive particles are disposed nearthe surface of the electrically insulating adhesive base layer” meansthat the electrically conductive particles 13 are completely pressed,embedded and disposed into the electrically insulating adhesive baselayer 11. In the case of FIG. 1B, the anisotropic electricallyconductive film 10 according to an embodiment of the present inventionhas a laminated structure, in which the electrically insulating adhesivebase layer 11 and the electrically insulating adhesive cover layer 12are laminated together and the electrically conductive particles 13 aredisposed near the interface therebetween. Here, “the electricallyconductive particles 13 are disposed near the interface between theelectrically insulating adhesive base layer 11 and the electricallyinsulating adhesive cover layer 12” means that the electricallyconductive particles 13 are located at the interface between the twolayers, or the electrically conductive particles 13 are completelypressed, embedded and disposed either into the electrically insulatingadhesive base layer 11 or into the electrically insulating adhesivecover layer 12.

Furthermore, in the anisotropic electrically conductive film 10according to an embodiment of the present invention, two or moreelectrically conductive particles 13 are grouped together to configureelectrically conductive particle groups 14, and the electricallyconductive particle groups 14 each has a structure disposed in a latticepoint region 15 of a planar lattice pattern (dotted line in FIG. 2). InFIGS. 1A, 1B, and 2A, the planar lattice pattern is assumed to run alongthe longitudinal direction of the anisotropic electrically conductivefilm 10 and the direction (short-side direction) orthogonal to thelongitudinal direction. However, the entire lattice pattern may beassumed to be inclined with respect to both of the longitudinaldirection and the short-side direction. With inclined pattern, an effectof improving capturability to bumps can be expected.

(Planar Lattice Pattern)

Examples of the planar lattice pattern assumed for the anisotropicelectrically conductive film include a rhombic lattice, a hexagonallattice, a square lattice, a rectangular lattice, a parallelotopelattice, and the like. In particular, the hexagonal lattice capable ofclosest packing is preferable.

(Lattice Point Region)

The lattice point region 15 of the planar lattice pattern may be invarious shapes, for example, a circular, a triangular, a quadrilateral,a polygonal, or an amorphous-shaped. In particular, from the viewpointof having similarity with the electrically conductive particles in planview and easily preventing falling off the electrically conductiveparticles at the end portions, it is preferable that the center(centroid) of the lattice point region coincides with the lattice pointP of the planar lattice pattern, and particularly a circle centered onthe lattice point P is preferable.

(Shortest Distance between Adjacent Lattice Point Regions)

A shortest distance between the adjacent lattice point regions in theplanar lattice pattern, i.e., a shortest distance between the centers(centroids) of the adjacent lattice point regions, is preferably twiceor greater the average particle diameter of the electrically conductiveparticles 13 or equivalent to or greater than the size of the latticepoint region 15. An upper limit of the shortest distance between theadjacent lattice point regions is appropriately set depending on thebump layout. However, an interval of less than 200 times, morepreferably less than 100 times, and even more preferably less than 34times the average particle diameter of the electrically conductiveparticles may be provided in the longitudinal direction of the film.This is because the lattice lines may always exist along the bump widthdirection when the bump width is 200 μm and L/S=1. This is also because,in order to sufficiently capture the electrically conductive particles,two or more lattice lines or three or more lattice lines may exist alongthe bump width direction (here, these lattice lines need not be parallelto the bump width direction). When there is a plurality of latticelines, for example, even if the electrically conductive particles arelost so that only one electrically conductive particle exists in thelattice point, the lattice point can be used without any practicalproblems. This facilitates an increase in yield, thus advantageous interms of production costs. As long as three or more consecutive latticepoints having one electrically conductive particle do not occur in onelattice axis direction, it is possible to resolve this issue bydesigning the arrangement with a margin and thus, no practical problemarises. Here, when a bump is redundant, for example, in FOG (Film onGlass), the lattice points will be partially contacted; and thus, theshortest distance between the adjacent lattice point regions is morepreferably twice or greater and less than 20 times the electricallyconductive particle diameter. Within this range, even when theanisotropic electrically conductive film according to an embodiment ofthe present invention is applied to an anisotropic electricallyconductive connection, better initial conductivity (the initialconduction resistance) and conduction reliability after aging may beachieved and occurrences of short circuit may be further suppressed.

(Diameter of Lattice Point Region)

When the lattice point region is circular, a radius thereof ispreferably not less than two times and not more than seven times, morepreferably not less than two times and not more than five times theaverage particle diameter of the electrically conductive particle 13.This value can be appropriately set by the bump layout. Within thisrange, the occurrence of short circuit can be easily prevented thatspans across spacing between one bump and the other bump only, and doesnot span over a plurality of bumps. Furthermore, when a bump or aspacing between bumps is large enough with respect to the electricallyconductive particle diameter, the lattice point region may be arectangular shape where one side is less than 100 times, preferably notgreater than 50 times, further preferably not greater than 33 times theparticle diameter

Furthermore, the length of the lattice point region in the longitudinaldirection of the film is preferably not greater than half of the bumpwidth. This results in achieving the effect of stability of anisotropicconnection and capturing reliability.

(Electrically Conductive Particle Groups)

In an embodiment of the present invention, a reason for configuring the“electrically conductive particle group” 14 from two or moreelectrically conductive particles 13 is to prevent short circuit bycreating a set of electrically conductive particles that do not crossover a plurality of bumps tin other words, creating only a set Ofelectrically conductive particles that cross over only one bump and aspacing between one bump). The number of electrically conductiveparticles that configure the electrically conductive particle group maydiffer depending on the average particle diameter of the electricallyconductive particle, the lattice point pitch of a planar latticepattern, or the like, but the number is preferably not less than two andnot more than 200. Note that the electrically conductive particles onlyexist on a single plane, and preferably do not overlap.

Note that if the distance between the lattice points is set tosubstantially equivalent to the size of the electrically conductiveparticle group or greater, the electrically conductive particle groupsmay easily be identified.

(Shortest Distance between Adjacent Electrically Conductive Particles)

Additionally, a plurality of electrically conductive particles 13configuring the electrically conductive particle group 14 in the latticepoint region 15 may be disposed randomly or disposed regularly. However,a plurality of electrically conductive particles 13 preferably shouldnot make excessive contact with each other. This is to suppress shortcircuit, In the case where the electrically conductive particles are notin contact with each other, the shortest distance between the adjacentelectrically conductive particles is not less than 25% of the averageparticle diameter of the electrically conductive particle.

Note that in the case where the electrically conductive particles 13 areregularly arranged within the electrically conductive particle groups14, the number of the electrically conductive particles is preferablynot less than 3, more preferably not less than 4. In such a case, thelattice point region including the electrically conductive particlegroup 14 may be a circle, in which the electrically conductive particlesare inscribed. Alternatively, a polygon shape including not less than 3electrically conductive particles may be a lattice point region. Inaddition, although not illustrated in the figure, the electricallyconductive particles configuring the electrically conductive particlegroups may be arranged in a single line at a predetermined distance(preferably not less than 0.5 times the electrically conductive particlediameter), or may be arranged in a manner that two lines cross in an Xshape (it may be arranged such that a plurality of lines may intersecteach other in a single line). In the case where the direction of anarrangement in a single line is aligned in all the electricallyconductive particle groups, there is no line composed of electricallyconductive particles at lattice points and no electrically conductiveparticles in the region without lattice points. However, when viewedmacroscopically in plan view, the line composed of electricallyconductive particles seems to exist as a dotted line. The arrangementdirection may be a longitudinal direction or a short-side direction ofthe anisotropic electrically conductive film. The arrangement directionmay also be a direction intersecting longitudinal or short-sidedirections. Furthermore, the arrangement direction of the “arrangementin a single line” may be regularly changed.

If the lattice point region of the electrically conductive particlegroups composed of three electrically conductive particles istriangular, it is preferable that at least two out of three sides arenot parallel either to the longitudinal direction of the anisotropicelectrically conductive film or to the short-side direction orthogonalthereto, and more preferably all of the three sides satisfy the aboveconditions. If the sides of the triangular shape are not parallel to thelongitudinal direction, it can be expected that occurrence of shortcircuit is suppressed, and if the sides of the triangular shape are notparallel to the short-side direction, the electrically conductiveparticles are not disposed in a straight line at the end of the bump, soit can be expected that variation in the number of captured electricallyconductive particles for each bump is suppressed.

Furthermore, the triangular shape of the lattice point region formed bythe electrically conductive particle groups composed of threeelectrically conductive particles may or may not the an equilateraltriangle. The triangular shape protruding in the longitudinal directionside or the short-side direction of the anisotropic electricallyconductive film is preferred for the following reasons (the triangularshape may be an isosceles triangle because of being easy to understandthe arrangement form). If it is a triangle protruding in thelongitudinal direction side, the distance in the spacing between thebumps becomes relatively wide, thereby preventing the occurrence ofshort circuit. Alternatively, if it is a triangle protruding in theshort-side direction, the sides of the triangle intersect at an acuteangle with respect to the bump end portions; and thus, an effect ofbeing easily captured the electrically conductive particles particularlyin the case of fine pitches can be expected.

In this case, it is preferable that circumscribed lines in the filmlongitudinal direction side of the electrically conductive particlesconstituting this side exist so as to penetrate the each electricallyconductive particle.

The case, in which the lattice point region of the electricallyconductive particle group composed of four electrically conductiveparticles is a quadrilateral shape, may be considered similarly to thecase of the triangular shape, because the quadrilateral shape may beconsidered as a combination of two triangles. Note that thequadrilateral shape may be a square, a rectangle, or a parallelogram,which are configured from two triangles of the identical shape, or mayalso be a quadrilateral shape such as a trapezoidal shape configured bycombining triangles of the different shapes. Alternatively, all of thesides, lengths or angles of the quadrilateral shape may be different.Note that, in the case where the lattice point region of theelectrically conductive particle group composed of four electricallyconductive particles is a parallelogram, it may be a combination of twoequilateral triangles, but it need not he an equilateral triangle. Alsoin this case, it is preferable that at least two sides are not paralleleither to the longitudinal direction of the anisotropic electricallyconductive film or to the short-side direction orthogonal thereto forthe same reason as in the case of the triangle.

The case, in which the gird point region of the electrically conductiveparticle group composed. of five electrically conductive particles is apentagonal shape, may be considered similarly to the case of thetriangular shape, because the pentagonal shape is a combination of threetriangles or a combination of a triangle and a quadrilateral. Even thecase, in which the lattice point region of the electrically conductiveparticle group composed of six or greater electrically conductiveparticles is a corresponding polygon shape, may be considered similarlyto the case of the following polygons, because the polygon shape is acombination of triangles, or a triangle and a quadrilateral or pentagon.Furthermore, the lattice point region may he regarded as a circle(including an ellipse). Electrically conductive particles may exist atthe center of the circle. This is because a polygon shape formed bycombining triangles may be regarded as a circle.

Note that, as illustrated in FIG. 2B (an embodiment for the case ofquadrilateral of a square lattice shape), the regular arrangement of theelectrically conductive particles configuring the electricallyconductive particle group may be identical in all electricallyconductive particle groups. Alternatively, as illustrated in FIG. 2C (anembodiment, in which the number of electrically conductive particlesdecreases or increases one by one repeatedly within a certain range),may be changed regularly. Alternatively, as illustrated in FIG. 2D (anembodiment, in which a length of a base of an isosceles triangleincreases by a constant length), the shape may be regularly changed withthe same number of electrically conductive particles. As illustrated inFIG. 2E (an embodiment in which a quadrilateral of the square latticeshape is rotated), the angle relative to the longitudinal direction ofthe film may be regularly changed, while the regular arrangement is ofthe same number of electrically conductive particles and the same shape.Note that, the regular arrangement of the electrically conductiveparticles configuring the electrically conductive particle group is notlimited to the embodiments illustrated in these figures, and from theviewpoint of the number of electrically conductive particles, the shapeof the electrically conductive particle group, and the like embodimentsof various regular changes may be combined. Such a combination canaccommodate various modifications not only in the hump layout, but alsoin compounding of the electrically insulating binder of the anisotropicelectrically conductive film, crimping conditions of the anisotropicconnection, or the like.

If the regular arrangement changes its arrangement regularly, the sideformed of the regular arrangement of the electrically conductiveparticles configuring the electrically conductive particle group in apart of the lattice points where such a change is present, may include aside parallel to the longitudinal direction of the anisotropicelectrically conductive film and the short-side direction orthogonalthereto. The electrically conductive particle groups are arranged in alattice form; thus, for example, when the longitudinal direction of thebump is large enough compared to the electrically conductive particlegroup, a plurality of lattice points may exist in the longitudinaldirection of the bump. In such a case, the electrically conductiveparticles existing at the end portions of the bump are captured by anyone of the electrically conductive particles at the lattice points.Thus, there is less concern that the conduction resistance becomesunstable because the number of supplements of the electricallyconductive particles is decreased. Therefore, by obtaining anarrangement of the electrically conductive particles that can easilygrasp the state of the anisotropic electrically conductive film duringproduction or after connection thereof, the accuracy of analyzingfactors is improved, thereby facilitating the reduction of total cost.For example, when the film illustrated in FIG. 2D or FIG. 2E iscontinuously moved in one direction (longitudinal direction which is thewinding and unwinding direction of the film, and the direction of theproduction line when the anisotropic connection is continuouslyperformed), it is easy to detect defects because the manner of change isregular. For example, by scrolling up and down while displaying the FIG.2E on a display, the movement of the anisotropic electrically conductivefilm in the actual production line can be simulated. Hence, it isunderstood that the discrimination between an abnormal state having adiscontinuous change and a state having no change can be facilitated ina state where the regular arrangement of the electrically conductiveparticles continuously changes. As described above, in the presentinvention, the regular arrangement of the electrically conductiveparticles configuring the electrically conductive particle group mayadopt various forms. This contributes to the method of designing thearrangement of electrically conductive particles in the anisotropicelectrically conductive film and becomes a part of the presentinvention.

(Number of Adjacent Electrically Conductive Particles)

Further, as an index for evaluating the electrically conductive particlegroup, the number of electrically conductive particles disposed adjacentto the periphery of any electrically conductive particle can be used.Here, “periphery of the electrically conductive particle” means aconcentric circle with a radius of 2.5 r that can be drawn on a planesurface of the film, when the electrically conductive particles areassumed to be spheres and their average particle diameter is r.

Further, “adjacent” means a state where the electrically conductiveparticle is in contact with or at least partially overlaps with theconcentric circle. The number of adjacent electrically conductiveparticles can be measured from the observation result of plan view. Thenumber of adjacent electrically conductive particles is preferably notless than 1 and not more than 14 and more preferably not less than 1 andnot more than 10. Setting of such limit is preferred because theshortest distance between bumps in the case of fine pitch is, forexample, less than four times the electrically conductive particlediameter. In other words, setting such limit accomplishes bothcharacteristics, i.e., suppresses occurrences of short circuit due toexcessive aggregation of the electrically conductive particles, andprevents occurrences of anisotropic connection failure due toexcessively loose electrically conductive particles.

(Electrically Conductive Particles)

As the electrically conductive particles 13, a the electricallyconductive particles used in a known anisotropic electrically conductivefilm can be appropriately selected and used. Examples of theelectrically conductive particles include metal particles such asnickel, copper, silver, gold, and palladium, and metal-coated resinparticles, in which the surface of resin particles such as polyamide andpolybenzoguanamine, and the like are coated with metals such as nickel.And the average particle diameter of the electrically conductiveparticles is preferably not less than 1 μm and not greater than 30 μm,and from the viewpoint of handleability during production, preferablynot less than 1 μm and not greater than 10 μm, and more preferably notless than 2 μm and not greater than 6 μm. As described above, theaverage particle diameter can be measured by using an image-type orlaser-type particle size analyzer.

The amount of electrically conductive particles to be present in theanisotropic electrically conductive film depends on the lattice pointpitch of the planar lattice pattern, the average particle diameter ofthe electrically conductive particles, and the like, and is generallynot less than 300/mm² and not greater than 40000/mm².

(Electrically Insulating Adhesive Base Layer)

As the electrically insulating adhesive base layer 11, the layer used asan electrically insulating adhesive base layer in a known anisotropicelectrically conductive Him can be appropriately selected and used.Examples that can be used include a photoradical polymerizable resinlayer containing an acrylate compound and a photoradical polymerizationinitiator, a thermal radical polymerizable resin layer containing anacrylate compound and a thermal radical polymerization initiator, athermal cationic polymerizable resin layer containing an epoxy compoundand a thermal cationic polymerization initiator, a thermal anionicpolymerizable resin layer containing an epoxy compound and a thermalanionic polymerization initiator, and the like, or a curable resin layerthereof. In addition, these resin layers may appropriately contain asilane coupling agent, a pigment, an antioxidant, an ultravioletabsorber, and the like, as necessary.

Note that the electrically insulating adhesive base layer 11 may beformed by forming a film using a coating composition containing a resinas described above by a coating method and then drying, further followedby curing, or by forming a film in advance by a known method.

The thickness of shell electrically insulating adhesive base layer 11may be not less than 1 and not greater than 60 μm, preferably not lessthan 1 μm and not greater than 30 μm, and more preferably not less than2 μm and not greater than 1 μm.

(Electrically Insulating Adhesive Cover Layer)

As the electrically insulating adhesive cover layer 12, the cover layerused as an electrically insulating adhesive cover layer in a knownanisotropic electrically conductive film can be appropriately selectedand used. Alternatively, the cover layer formed from the same materialas that of the electrically insulating adhesive base layer 11 asdescribed earlier can be also used.

Note that the electrically insulating adhesive cover layer 12 may beformed by forming a trim using a coating composition containing a resinas described above by a coating method and then drying, further followedby curing, or by forming a film in advance by a known method.

The thickness of such electrically insulating adhesive cover layer 12 ispreferably not less than 1 μm and not greater than 30 μm and morepreferably not less, than 2 μm and not greater than 15 μm.

Furthermore, electrically insulating filter such as silica fineparticles, alumina, and aluminum hydroxide may be added, as necessary,to the electrically insulating adhesive base layer 11 or theelectrically insulating adhesive cover layer 12. The amount of theelectrically insulating filler blended is preferably not less than 3 andnot greater than 40 parts by mass per 100 parts by mass of the resinconstituting these layers. With this range of blending amount, even henthe anisotropic electrically conductive film 10 is melted duringanisotropic electrically conductive connection, unnecessary movement ofthe electrically conductive particles 13 by the molten resin can besuppressed.

(Laminating Electrically Insulating Adhesive Base Layer and ElectricallyInsulating Adhesive Cover Layer)

Note that lamination of the electrically insulating adhesive base layer11 and the electrically insulating adhesive cover layer 12 with theelectrically conductive particles 13 being interposed therebetween canbe performed by using a known method. In this ease, the electricallyconductive particles 13 exist near the interface of these layers. Here,“exist near the interface” indicates that a part of the electricallyconductive particles intrudes into one layer, the remainder intrudesinto the other layer.

<Production of Anisotropic Electrically Conductive Film>

Next, a method of producing an anisotropic electrically conductive filmaccording to an embodiment of the present invention will be described.In other words, the anisotropic electrically conductive film has astructure in which electrically conductive particles are disposed on ornear the surface of the electrically insulating adhesive base layer(FIG. 1A), or has a structure in which the electrically insulatingadhesive base layer and the electrically insulating adhesive cover layerare laminated together and the electrically conductive particles aredisposed near the interface therebetween. Here, the electricallyconductive particle groups configured from two or more electricallyconductive particles and the electrically conductive particle groups aredisposed in a lattice point region of a planar lattice pattern (FIG.1B). The method of producing an anisotropic electrically conductive filmhaving a structure, in which electrically conductive particles aredisposed on or near the surface of the electrically insulating adhesivebase layer, comprises the following steps (i) to (iv), and the method ofproducing an anisotropic electrically conductive film having astructure, in which the electrically insulating adhesive base layer andthe electrically insulating adhesive cover layer are laminated togetherand the electrically conductive particles are disposed near theinterface therebetween, comprises the following steps (i) to (v). Eachstep will be described in detail with reference to the drawings. Notethat the present invention is not limited to these production methods.

(Step (i))

First, as illustrated in FIG. 3A, a transfer body 100, having a convexportion 101 corresponding to the lattice point region of a planarlattice pattern, formed on the surface thereof is prepared. The convexportion 101 may be of various shapes such as a substantially columnarshape, a substantially hemispherical shape, a rod shape, and the like.The term “substantially” is used because not only the convex portion mayhave the same constant width along the height direction, but also theconvex portion may have the width, which narrows toward the top. The“substantially columnar shape” herein is a substantially cylindricalshape or substantially prism shape (a triangular prism, a square prism,a hexagonal prism, and the like). The substantially columnar shape ispreferable.

The height of the convex portion 101 can be determined depending on theterminal pitch, the terminal width, the spacing width, the averageparticle diameter of the electrically conductive particles, and the likewhere anisotropic electrically conductive connection should be provided.And the height is preferably not less than 1.2 times and less than fourtimes the average particle diameter of the electrically conductiveparticles used. In addition, the half width (width at half height) ofthe convex portion 101 is preferably not less than two and not greaterthan seven times, and more preferably not less than two and not greaterthan five times the average particle diameter of the electricallyconductive particles. Setting height and width within the aboveprescribed range can achieve an effect to prevent the event of sheddingor loss of the electrically conductive particles continuously.

Furthermore, the convex portion 101 preferably has a top surface flatenough for the electrically conductive particles to be deposited stably.

* Specific Example of the Transfer Body

The transfer body to be prepared in the step (i) can be prepared byusing a known method. For example, a transfer body can be prepared byprocessing a metal plate to prepare a master, a curable resincomposition is then applied thereto, followed by curing. Specifically, aflat metal plate is cut and processed to prepare a transfer body masterformed with a concave portion corresponding to a convex portion. Theconcave portion forming surface of the master is then coated with aresin composition that configures the transfer body followed by curing.After curing, the composition is separated from the master to obtain atransfer body. The region surrounded by the contour recognizable whenthe convex portion is viewed in plan view, corresponds to the latticepoint region of a planar lattice pattern.

(Step (ii))

Next, as illustrated in FIG. 3B, at least two slightly adhesive portions102 are formed on the top surface of the convex portion 101 of thetransfer body 100, where a plurality of convex portions 101 are formedin a planar lattice pattern on the surface of the transfer body 100. Theshortest distance between the slightly adhesive portions 102 is setpreferably to not less than 0.25 times, more preferably not less than0.5 times the average particle diameter of the applied electricallyconductive particle.

* Slightly Adhesive Portion of the Transfer Body

The slightly adhesive portion 102 exhibits an adhesive force capable oftemporarily holding the electrically conductive particles until theelectrically conductive particles are transferred to the electricallyinsulating adhesive base layer configuring the anisotropic electricallyconductive film. Such slightly adhesive portions 102 are formed at leaston the top surface of the convex portions 101. Therefore, entire convexportions 101 may possess slight adhesiveness. However, in order toprevent occurrence of unintended aggregation of the electricallyconductive particles, two or more slightly adhesive portions 102separated apart from each other are provided in an embodiment of thepresent invention. In addition, the thickness of the slightly adhesiveportion 102 may be appropriately determined depending on the material ofthe slightly adhesive portion 102, the particle diameter of theelectrically conductive particles, and the like. “Slightly adhesive”means that the adhesive force is weaker than that of the electricallyinsulating adhesive base layer when the electrically conductiveparticles are transferred to the electrically insulating adhesive baselayer.

As such a slightly adhesive portion 102, a slightly adhesive portionused in a known anisotropic electrically conductive film may be used.For example, the slightly adhesive portion can he formed by applying asilicone-based adhesive composition on the top surface of the convexportions 101.

Not that when producing an anisotropic electrically conductive filmhaving electrically conductive particles regularly arranged asillustrated in FIGS. 2B to 2E, a step may be formed in the concaveportions the transfer body master so that the slightly adhesive layercorresponding to the regularly arranged pattern of the electricallyconductive particles is formed on the convex portion of the transferbody. Alternatively, the slightly adhesive layer may be formed on thetop surface of the convex portion of the transfer body by using a knownmethod such as a screen printing method or a photolithography method.

(Step (ii))

Next, as illustrated in FIG. 3G, electrically conductive particles 103are deposited to the slightly adhesive portion 102 of the convexportions 101 of the transfer both 100. Specifically, the electricallyconductive particles 103 may be dispersed from above on the convexportions 101 of the transfer body 100, and the electrically conductiveparticles 103 that are not deposited to the slightly adhesive portions102 may be blown away by using a blower. Thus, a plurality ofelectrically conductive particles 103 are deposited to a convex portion101, from which the electrically conductive particle groups 114 areconfigured.

Note that the direction of the surface may be reversed from FIG. 3G, andthe top surface of the protrusion may be contacted to the surface onwhich the electrically conductive particles are spread all over. This isto avoid unnecessary stress applied to the electrically conductiveparticles. Thus, by depositing only electrically conductive particlesnecessary for the arrangement on the top surface of the protrusion, itis easy to recover and reuse electrically conductive particles, which ismore economical in comparison with the method of filling theelectrically conductive particles in an opening portion and removinglater. Note that in the case of the method of filling the electricallyconductive particles in an opening portion and removing later, there isa problem that unnecessary stress is easily applied to the unfilledelectrically conductive particles.

(Step (iv))

Next, as illustrated in FIG. 3D, when the electrically insulatingadhesive base layer 104 constituting the anisotropic electricallyconductive film is overlapped and pressed on the surface of the transferbody 100 at a side on which the electrically conductive particle groups114 are deposited, the electrically conductive particle groups 114 aretransferred to one side of the electrically insulating adhesive baselayer 104 (FIG. 3E). In this case, it is preferable that the transferbody 100 is overlapped and pressed on the electrically insulatingadhesive base layer 104 such that the convex portions 101 face downward.This is because the electrically conductive particles not stuck to thetop surface of the convex portion are easily removed by blowing whilefacing downward. Note that in this step, the transferred electricallyconductive particles may be further pressed into the electricallyinsulating adhesive base layer 11. For example, the transferredelectrically conductive particles may further he pressed by the transferbody, or the transferred surface of the electrically conductive particleof the electrically insulating adhesive base layer may be generallypressed by a heat pressing plate. Thereby, the anisotropic electricallyconductive film of FIG. 1A, having a structure, in which theelectrically conductive particles are disposed on or near the surface ofthe electrically insulating adhesive base layer, is obtained.

(Step (v))

Furthermore, as illustrated in FIG. 3F, the electrically insulatingadhesive cover layer 105 is laminated on the electrically insulatingadhesive base layer 104, on which the electrically conductive particles103 are transferred, from a side, on which the electrically conductiveparticles are transferred. Thus, the anisotropic electrically conductivefilm 200 (FIG. 1B) according to an embodiment of the present inventionis obtained.

<Connecting Structure>

The anisotropic electrically conductive film according to an embodimentof the present invention is disposed between the terminal (such as abump) of the first electronic component (such as an IC chip) and theterminal (such as a hump or a pad) of the second electronic component(such as a wiring hoard), and then cured by using thermocompressionbonding from the first or second electronic component side toanisotropically electrically conductively connect the terminals. Then aconnecting structure such as so-called COG (chip on glass), FOG (film onglass), or the like can be obtained., in which short circuit or poorconduction is suppressed.

EXAMPLES

Hereinafter, the present invention will be described in detail,

Example 1

A 2 mm thick nickel plate was prepared. A cylindrically-shaped concaveportion (an inner diameter 8 μm and a maximum depth 8 μm) was formed ina tetragonal lattice pattern, and linear grooves having a depth of 1 μmand a width of 1 μm were randomly formed at the bottom (the total areaof the grooves was within 70% of the total bottom area). Thus, thetransfer body master was obtained. The distance between adjacent concaveportions was 12 μm. Accordingly, the density of the concave portions was2500/mm². The inner diameter of the concave portion and the distancebetween the adjacent concave portions correspond to a convex portiondiameter of the transfer body and the shortest distance between theadjacent convex portions.

The resultant transfer body master was coated with a photopolymerizableresin composition containing 60 parts by mass of phenoxy resin (YP-50,Nippon Steel & Sumikin Chemical Co., Ltd i, 29 parts by mass of acrylateresin (M208, Toagosei Co., Ltd,), and 2 parts by mass ofphotopolymerization initiator (IRGACURE184, BASF Japan Ltd.) on a PET(polyethylene terephthalate) film to a dried thickness of 30 μm. Afterdrying for live minutes at 80° C., light irradiation at 1000 mJ wasperformed with a high pressure mercury lamp to create the transfer body.

The transfer body was peeled off from the master and wound around astainless steel roll having a diameter of 20 cm such that the convexportions were on the outer side. This roll was rotated andsimultaneously brought into contact with an adhesive sheet obtained byimpregnating a nonwoven fabric with a slightly adhesive compositioncontaining 70 parts by mass of epoxy rosin (jER828, Mitsubishi ChemicalCorporation) and 30 parts by mass of phenoxy resin (NT-50, Nippon Steel& Sumikin Chemical Co., Ltd.), The slightly adhesive composition wasdeposited on the top surface of the convex portions to form a 1 μm thickslightly adhesive layer. Thus, the transfer body was obtained.

The slightly adhesive layer was formed in a dot shape due to the groovesprovided at the bottom of the transfer body master.

The electrically conductive particles having an average particlediameter of 4 μm (nickel plated resin particles (AUL704, SekisuiChemical Co., Ltd.)) were dispersed on the surface of the transfer body,and subsequently, blown away to remove the electrically conductiveparticles, which were not deposited to the slightly adhesive laver.

The transfer body having electrically conductive particles depositedthereon was pressed against a sheet-like thermosetting electricallyinsulating adhesive film having a thickness of 5 μm that serves as theelectrically insulating adhesive base layer (a film formed from anelectrically insulating resin composition containing 40 parts by mass ofphenoxy resin (YP-50, Nippon Steel & Sumikin Chemical Co., Ltd.), 40parts by mass of epoxy resin (jER828, Mitsubishi Chemical Como ration),2 parts by mass of cationic curing agent (SI-60L, Sanshin ChemicalIndustry Co., Ltd.), and 20 parts by mass of Silica fine particlesfiller (Aerosil RY200, Nippon Aerosil Co., Ltd.)). The transfer body waspressed at a temperature of 50° C. and a pressure of 0.5 MPa from theside on which electrically conductive particles were deposited. Thus,the electrically conductive particles were transferred to theelectrically insulating adhesive base layer.

On the surface of the resulting electrically insulating adhesive baselayer, on which the electrically conductive particles were deposited,another sheet-like electrically insulating adhesive film having athickness of 15 μm (a film formed from a thermosetting resin compositioncontaining 60 parts by mass of phenoxy resin (YP-50. Nippon Steel &Sumikin Chemical Co., Ltd.), 40 parts by mass of epoxy resin (jER828,Mitsubishi Chemical Corporation), and 2 parts by mass of cationic curingagent (SI-60L, Sanshin Chemical Industry Co., Ltd.)) was overlapped as atransparent electrically insulating adhesive cover layer and laminatedtogether at a temperature of 60° C. and a pressure of 2 MPa. Thereby,the anisotropic electrically conductive film was obtained.

Example 2

The anisotropic electrically conductive film was obtained by repeatingthe Example 1 except for changing the distance between the adjacentconcave portions to 8 μm when preparing the transfer body master. Notethat the density of the concave portions of the transfer body master was3900/mm².

Example 3

The anisotropic electrically conductive film was obtained by repeatingthe Example 1 except for changing the inner diameter of the concaveportion to 12 μm and the distance between the adjacent concave portionsto 8 μm when preparing the transfer body master. Note that the densityof the concave portions of the transfer body master was 2500 mm².

Example 4

The anisotropic electrically conductive film was obtained by repeatingthe Example 1 except for changing the inner diameter of the concaveportion to 20 μm and the distance between the adjacent concave portionsto 20 μm when preparing the transfer body master was. Note that thedensity of the concave portions of the transfer body master was625/min².

Comparative Example 1

The anisotropic electrically conductive film was obtained by repeatingthe Example 1 except for changing the inner diameter of the concaveportion to 12 μm and the distance between the adjacent concave portionsto 4 μm when preparing the transfer body master. Note that the densityof the concave portions of the transfer body master was 3900/mm².

Comparative Example 2

The anisotropic electrically conductive film was obtained by repeatingthe Example 2 except that in the Example 2, a dispersion and blowingtreatment for electrically conductive particles was performed twice.

Comparative Example 3

The anisotropic electrically conductive film was obtained by repeatingthe Example 1 except for changing the inner diameter of the concaveportion to 8 μm and the distance between the adjacent concave portionsto 80 μm when preparing the transfer body master. The density of concaveportions was 130/mm².

Evaluation> (Evaluation Related to Lattice Point Region)

The shortest distance between the adjacent electrically conductiveparticles in the (circular) lattice point region, the shortest distancebetween the adjacent lattice point regions, and the diameter of thelattice point region, of the anisotropic electrically conductive filmsin the Examples and Comparative Examples were measured by using anoptical microscope (MX50, Olympus Co., Ltd.). The obtained results areshown in Table 1.

(Number of Adjacent Electrically Conductive Particles)

One hundred electrically conductive particles of the anisotropicelectrically conductive films of the Examples and Comparative Exampleswere arbitrarily selected When each electrically conductive particle isassumed to be a sphere, the number of electrically conductive particlesat least partially overlapping a concentric circle having a radius of2.5 r in the horizontal direction, where r denotes the average particlediameter thereof, was measured by using an optical microscope (MX50,Olympus Co., Ltd.). The obtained results (minimum number (MIN) andmaximum number (MAX)) are shown in Table 1. Practically, the number ispreferably not more than 10.

Note that the measurement observation showed that in the ComparativeExample 2 the electrically conductive particles were in a dense statebecause the dispersion and blowing treatment was repeated twice. Thiswas also understood from the fact that the number of adjacentelectrically conductive particles increased.

(Initial Conductivity (Initial Conduction Resistance))

The anisotropic electrically conductive films of the Examples and theComparative Examples were used to form an anisotropic electricallyconductive connection between the IC chip having a gold bump with aspacing between bumps of 12 μm, height of 15 μm, and a diameter of 30×50μm and a glass substrate provided with a wiring of 12 μm spacing, underconditions of 180° C., 60 MPa, and 5 seconds, to obtain a connectingstructure. For the resulting connecting structure, an initial conductionresistance value was measured by using a resistance measuring instrument(digital multimeter, Yokogawa Electric Corporation). The obtainedresults are shown in Table 1. The resistance of not greater than 1 Ω isdesirable.

(Conduction Reliability)

The connecting structure used for measuring of the initial conductionresistance value was placed in an aging tester set to a temperature of85° C. and a humidity of 85%, and the conduction resistance value after500 hours of standing was measured in the same manner as the initialconduction resistance. The obtained results are shown in Table 1. Theresistance of not greater than 5 Ω is desirable.

(Occurrence Rate of Short Circuit)

The same connecting structure as used for the initial conductionresistance was prepared to check the presence or absence of occurrenceof a short circuit between the adjacent wirings. The obtained resultsare shown in Table 1. The occurrence rate of short circuit of notgreater than 50 ppm is desirable.

TABLE 1 Comparative Examples Examples 1 2 3 4 1 2 3 Average ParticleDiameter of [μm] 4 4 4 4 4 4 4 Electrically conductive ParticlesShortest Distance Between [μm] 2 1 2 2 2 0 1 Adjacent Electricallyconductive Particles Diameter of Lattice Point Region [μm] 8 8 12 20 128 8 Shortest Distance Between [μm] 12 8 8 20 4 8 80 Adjacent LatticePoint Regions Number of Adjacent Electrically MIN 1 1 2 2 5 7 0conductive Particles MAX 4 6 8 10 12 15 4 Initial Conduction Resistance[Ω] 0.2 0.2 0.2 0.2 0.2 0.2 1 Conduction Reliability [Ω] 4 4 4 4 4 4 15Occurrence Rate of Short Circuit [ppm] <50 <50 <50 <50 200 500 <50

As is clear from the results in Table 1 that the connecting structureusing the anisotropic electrically conductive films of Examples 1 to 4showed satisfactory results for each of the evaluation items of initialconductivity (initial conduction resistance), conduction reliability,and occurrence rate of short circuit.

On the other hand, in the anisotropic electrically conductive films ofthe Comparative Examples 1 and 2, there were many adjacent electricallyconductive particles in plan view; thus the occurrence rate of shortcircuit was unfavorably very high compared to the Examples. In theanisotropic electrically conductive film of the Comparative Example 3,the number of electrically conductive particles was too sparse, thus theconduction reliability was insufficient, and the initial conductivitywas also interior compared to the Examples.

Example 5

The electrically insulating adhesive base layer was prepared in the samemanner as in the Example 1 except that phenoxy resin (YP-50, NipponSteel, & Sumikin Chemical Co., Ltd.) was changed from 40 to 50 parts bymass, silica fine particle filler (Aerosil RY200, Nippon Aerosil Ltd.)was changed from 20 to 10 parts by mass, and the thickness was changedfrom 5 μm to 20 μm from Example 1 without using the electricallyinsulating adhesive cover layer. Then, the electrically conductiveparticles were transferred and pressed to obtain an anisotropicelectrically conductive film, in which the electrically conductiveparticles were disposed in the electrically insulating adhesive baselayer, as illustrated in FIG. 1A. As in the case of Example 1, theconnecting structure using this anisotropic electrically conductive filmshowed satisfactory results for each of the evaluation items of initialconductivity (initial conduction resistance), conduction reliability,and occurrence rate of short circuit.

Example 6

In order to produce the anisotropic electrically conductive film having,electrically conductive particles regularly arranged as illustrated inFIG. 2B, the anisotropic electrically conductive film was obtained inthe same manner as in Example 1 except for using the transfer bodymaster having a concave portion (size 14 μm×14 μm (a step was providedat each corner of the concave portion so that the slightly adhesivelayer was provided only at each corresponding corner of the transferbody)), a concave portion density of 125/mm², and a distance between theadjacent concave portions of 75 μm; providing the slightly adhesivelayer at the corner of the top surface of the convex portion of thetransfer body so that the number of electrically conductive particles inthe electrically conductive particle group was four and the distancebetween the electrically conductive particles in the electricallyconductive particle group was 4 μm; changing the amount of the phenoxyresin (YP-50, Nippon Steel & Sumikin Chemical Co., Ltd.) and the silicafine particle filler (Aerosil RY200, Nippon Aerosil Co., Ltd.) of theelectrically insulating adhesive base layer of Example 1 from 40 partsby mass to 50 parts by mass and from 20 parts by mass to 10 parts bymass, respectively. The density of number of electrically conductiveparticles was 500/mm.

In addition, the resulting anisotropic electrically conductive film wasinterposed between a glass substrate (ITO solid electrode) and aflexible wiring board (bump width: 200 μm, L (line)/S, wiring height of10 μm) to establish an anisotropic conduction connection under theconditions of 180° C. 5 MPa-5 seconds so that the connecting bump lengthwas 1 mm, and thus, the connecting structure for evaluation wasobtained. For the resulting connecting structure, the “initialconduction resistance value”, and the “conduction reliability” afterbeing placed in a thermostatic chamber with a temperature of 85° C. anda humidity of 85% RH for 500 hours were evaluated as follows: theconduction resistance was measured using a four terminal method at acurrent of 1 A using a digital multimeter (34401A, manufactured byAgilent Technologies. Inc.), the “initial conductivity” was evaluated assatisfactory when the measured value was not greater than 2 Ω andevaluated as poor when the measured value exceeds 2 Ω, and the“conduction reliability” was evaluated as satisfactory when the measuredvalue was not greater than 5 Ω and evaluated as poor when the measuredvalue was not less than 5 Ω. As a result, all the connecting structuresof the present Examples were evaluated as “satisfactory”. In addition,the “occurrence rate of short circuit” was measured in the same manneras in Example 1, and satisfactory results similar to Example 1 wereobtained.

Example 7

The anisotropic electrically conductive film was obtained in the samemanner as in Example 6 except for using the transfer body master havingthe concave portion density of 500/mm² and the distance of 31 μm betweenthe adjacent concave portions so that the density of number ofelectrically conductive particles was 2000/mm².

In addition, the resulting anisotropic electrically conductive film wasinterposed between a glass substrate and a flexible wiring board in thesame manner as in Example 6 to establish an anisotropic conductionconnection to obtain a connecting structure for evaluation. The resolingconnecting: structure was evaluated for “initial conductivity”,“conduction reliability”, and “occurrence rate of short. circuit” in thesame manner as in Example 6, and all were found to satisfactory.

Example 8

In order to produce the anisotropic electrically conductive film havingelectrically conductive particles regularly arranged as illustrated inFIG. 2C. the transfer body master having a concave portion size of 20μm×20 μm (a step was provided in the concave portion so that theslightly adhesive layer was provided only at the predetermined places ofthe transfer body), a concave portion density of 125/mm², and thedistance between the adjacent centers of 69 μm, was used, The number ofelectrically conductive particles of electrically conductive particlegroup was continuously changed to 6, 5, 4, and 3, and the shortestdistance between electrically conductive particles in the electricallyconductive particle groups was set to not less than 3 μm in any shape.Note that, the outer shapes are set to be approximately equal for anyshape. Furthermore, such a shape is one resembling a regular hexagon, aregular pentagon, a square, or a regular triangle, by adjusting thelength of either side of the shape accordingly. The anisotropicelectrically conductive film was obtained in the same manner as inExample 6, except providing the slightly adhesive layer on the topsurface of the convex portion of the transfer body. The density ofnumber of electrically conductive particles was 500/mm².

In addition, the resulting anisotropic electrically conductive film wasinterposed between a glass substrate and a flexible wiring hoard in thesame manner as in Example 6 to establish an anisotropic conductionconnection to obtain a connecting structure for evaluation. Theresulting connecting, structure was evaluated for “initialconductivity”, “conduction reliability”, and “occurrence rate of shortcircuit” in the same manner as in the Example 6, and all were found tobe satisfactory.

Example 9

The anisotropic electrically conductive film was obtained in the samemanner as in Example 8, except for using the transfer body master havinga concave portion density of 500/mm² and a distance between the adjacentconcave portions of 25 μm so that the density of number of theelectrically conductive particles was 2000/mm².

In addition, the resulting anisotropic electrically conductive film wasinterposed between a glass substrate and a flexible wiring board in thesame manner as in Example 6 to establish an anisotropic conductionconnection to obtain a connecting structure for evaluation. Theresulting connecting structure was evaluated for “initial conductivity”,“conduction reliability”, and “occurrence rate of short circuit” in thesame manner as in Example 5, and all were found to be satisfactory.

Example 10

In order to produce the anisotropic electrically conductive film havingelectrically conductive particles regularly arranged as illustrated inFIG. 2D, the anisotropic electrically conductive film was obtained inthe same manner as in Example 6, except for using the transfer bodymaster having a concave portion size of 20 μ×20 μm (a step was providedin the concave portion so that the slightly adhesive layer was providedonly at a predetermined location of the transfer body), a concaveportion density of 167/mm²; and a distance between the adjacent concaveportions of 57 μm; providing the slightly adhesive layer on the topsurface of the convex portion of the transfer body so that the number ofelectrically conductive particles in the electrically conductiveparticle group was three, and the shape of the electrically conductiveparticle group was an isosceles triangle, and the distance between theelectrically conductive particles was (4 μm, 12 μm, and 12 μm), or (8μm, 13 μm, and 13 μm). The density of number of the electricallyconductive particles was 500/mm².

In addition, the resulting anisotropic electrically conductive film wasinterposed between a glass substrate and a flexible wiring board in thesame manner as in Example 6 to establish an anisotropic conductionconnection to obtain a connecting structure for evaluation. Theresulting connecting structure was evaluated for “initial conductivity”,“conduction reliability”, and “occurrence rate of short circuit” in thesame manner as in Example 6, and all were found to satisfactory.

Example 11

The anisotropic electrically conductive film was obtained in the samemanner as in Example 10, except for using the transfer body masterhaving the concave portion density of 667/mm² and the distance betweenthe adjacent concave portions of 19 μm so that the density of number ofelectrically conductive particles was 2000/mm².

In addition, the resulting anisotropic electrically conductive film wasinterposed between a glass, substrate and a flexible wiring board in thesame manner as in Example 6 to establish an anisotropic conductionconnection to obtain a connecting structure for evaluation. Theresulting connecting structure was evaluated for “initial conductivity”“conduction reliability”, and “occurrence rate of short circuit” in thesame manner as in the Example 6, and all were found to be satisfactory.

Example 12

In order to produce the anisotropic electrically conductive film hayingelectrically conductive particles regularly arranged as illustrated inFIG. 2E, the anisotropic electrically conductive film was obtained inthe same manner as in Example 6, except for using the transfer bodymaster with the rectangular electrically conductive particle groups, theinclination of which was incrementally increased by 15 degrees in thelongitudinal direction and the short-side direction of the film,respectively. The density of number of electrically conductive particlewas 500/mm².

In addition, the resulting anisotropic electrically conductive film wasinterposed between a glass substrate and a flexible wiring board in thesame manner as in Example 6 to establish an anisotropic conductionconnection to obtain a connecting structure for evaluation. Theresulting connecting structure was evaluated for “initial conductivity”,“conduction reliability”, and “occurrence rate of short circuit” in thesame manner as in the Example 6, and all were found to be satisfactory.

Example 13

The anisotropic electrically conductive film was obtained in the samemanner as in Example 12, except for using the transfer body masterhaving a concave portion density of 500/mm², and the distance betweenthe adjacent concave portions of 31 μm so that the density of number ofelectrically conductive particles was 2000/mm².

In addition, the resulting anisotropic electrically conductive film wasinterposed between as glass substrate and as flexible wiring hoard thesame manner as in Example 6 to establish an anisotropic conductionconnection to obtain a connecting structure for evaluation. Theresulting connecting structure was evaluated for “initial conductivity”,“conduction reliability”, and “occurrence rate of short circuit” in thesame manner as in Example 5, and all were found to be satisfactory.

Note that, in Examples 6 to 13, another anisotropic electricallyconductive film was prepared and evaluated by repeating the respectiveExamples except that the method was employed, in which electricallyconductive particles were filled directly into a transfer mold having acot ca portion and the electrically conductive particles weretransferred to the electrically insulating adhesive base layer. As aresult, substantially the same results as in Examples 6 to 13 wereobtained.

INDUSTRIAL APPLICABILITY

For the anisotropic electrically conductive film according tar anembodiment of the present invention, the following is employed: atransfer body having a convex portion corresponding to a lattice pointregion of a planar lattice pattern, formed on the surface thereof, isused; two or more slightly adhesive portions are formed on the topsurface of the convex portion; the electrically conductive particles aredeposited on the slightly adhesive portions; and then the electricallyconductive particles are transferred to an electrically insulatingadhesive base layer. Therefore, the electrically conductive particlegroups configured from two or more electrically conductive particles aredisposed in a lattice point region of a planar lattice pattern.Therefore, use of anisotropic electrically conductive film obtained bythe production method according to an embodiment of the presentinvention Can achieve anisotropic electrically conductive connectionwhile significantly suppressing occurrences of short circuit and poorconduction between the IC chip and the wiring board having narrowpitches.

REFERENCE SIGNS LIST

10, 200 Anisotropic electrically conductive film

11, 104 Electrically insulating adhesive base layer

12, 105 Electrically insulating adhesive cover layer

13, 103 Electrically Conductive particle

14,114 Electrically conductive particle group

15 Lattice point region of a planar lattice pattern

100 Transfer body

101 Convex portion

102 Slightly adhesive portion

P Lattice point

1. An anisotropic electrically conductive film having a structure, inwhich electrically conductive particles are disposed on or near asurface of an electrically insulating adhesive base layer, wherein anelectrically conductive particle group is configured from two or moreelectrically conductive particles, the electrically conductive particlegroup is disposed in a lattice point region of a planar lattice pattern,and a centroid of the lattice point region coincides with the latticepoint of the planar lattice pattern.
 2. The anisotropic electricallyconductive film according to claim 1, wherein a shortest distancebetween adjacent electrically conductive particles is not less than 25%of an average particle diameter when electrically conductive particlesare not in contact with each other within the electrically conductiveparticle group.
 3. The anisotropic electrically conductive filmaccording to claim 1, wherein the lattice point region is a circlecentered on a lattice point.
 4. The anisotropic electrically conductivefilm according to claim 1, wherein the lattice point region of a planarlattice pattern is a circle centered on a lattice point, and a radius ofthe circle is not less than two times and not greater than seven timesthe average particle diameter of the electrically conductive particles.5. The anisotropic electrically conductive according to claim 1, whereinas shortest distance between adjacent lattice point regions is eithertwice or greater than the average particle diameter of the electricallyconductive particles, or equivalent to or greater than a size of thelattice point region.
 6. The anisotropic electrically conductive filmaccording to claim 1, wherein a plurality of electrically conductiveparticles in the lattice point region is not in contact with each other.7. The anisotropic electrically conductive film according to claim 1,wherein a plurality of electrically conductive particles in the latticepoint region is regularly arranged.
 8. The anisotropic electricallyconductive according to claim 1, wherein an electrically insulatingadhesive cover layer is laminated on the electrically insulatingadhesive base layer.
 9. The anisotropic electrically conductive filmaccording to claim 1, wherein electrically conductive particle group areconfigured from three or more electrically conductive particles, and twoor more sides of a polygonal shape including electrically conductiveparticles in the electrically conductive particle group are not parallelto the longitudinal direction of the film and the direction orthogonalthereto.
 10. The anisotropic electrically conductive film according toclaim 1, wherein the electrically insulating adhesive base layercontains an electrically insulating filler.
 11. The anisotropicelectrically conductive film according to claim wherein at least one ofthe electrically insulating adhesive base layer and the electricallyinsulating adhesive cover layer contains an electrically insulatingfiller.
 12. A connecting structure having a terminal of a firstelectronic component and a terminal of a second electronic componentbeing anisotropically electrically conductively connected by theanisotropic electrically conductive film described in claim
 1. 13. Amethod for producing a connecting structure comprising anisotropicallyelectrically conductively connecting a terminal of a first electroniccomponent and a terminal of a second electronic component by theanisotropic electrically conductive film described in claim
 1. 14. Aconnecting structure having a terminal of a first electronic componentand a terminal of a second electronic component being anisotropicallyelectrically conductively connected by the anisotropic electricallyconductive film described in claim
 8. 15. A method for producing aconnecting structure comprising anisotropically electricallyconductively connecting a terminal of a first electronic component and aterminal of a second electronic component by the anisotropicelectrically conductive film described in claim 8.